TORONTO — The family of a Toronto university student who was detained after surviving a bloody hostage-taking in Bangladesh said Monday they haven't been able to contact him for days and are concerned for his well-being.

Tahmid Hasib Khan, a 22-year-old permanent resident of Canada, has been in custody in Dhaka ever since the July 1 attack. The family doesn't know why he's being held, but they insist Khan is innocent.

"The more days go by, the more we're getting concerned because Bangladesh police and army, they don't have a very good human rights record,'' Khan's older brother, Talha Khan, said in an interview in Toronto.

Tahmid Khan, an undergraduate student studying global health at the University of Toronto, had travelled to Dhaka to visit family, with plans to go on to Nepal where he was to begin an internship this week.

Tahmid Hasib Khan's family fears authorities may suspect him of being linked to the attackers. (Photo: Facebook)

He was meeting friends at an upscale restaurant in Dhaka's diplomatic zone when he got caught up in the 10-hour hostage crisis.

A group of young Bangladeshi men held about 35 hostages over night, killing 20 of them, including 17 foreigners from Japan, Italy and India. Two police officers were also killed in the siege.

Khan was detained after the attack ended, and his family fears authorities may suspect him of being linked to the attackers, who have been identified as coming from well-off families.

"We want to know why he is being held, as a witness, or as a suspect,'' said Khan's brother, who is a Canadian citizen. "He was just in the wrong place at the wrong time. Nothing in his life points towards any sort of extremism.''

"The more days go by, the more we're getting concerned because Bangladesh police and army, they don't have a very good human rights record." —Talha Khan, brother of Tahmid Hasib Khan

While Khan's father was able to speak with his son twice in the early days of his detention, the family has not been able to reach him for a week, and isn't even sure where he is being held, his brother said.

"We know he is in Dhaka but where exactly we don't know,'' Talha Khan said.

"We've done everything that can be done. We've reached out to the government in Canada, we have reached out to the government in Bangladesh, now it's up to the authorities to make their decision. We just want them to not take so much time, and be just in whatever they do.''

The family has reached out to Foreign Affairs Minister Stephane Dion through a Canadian lawyer, but has not heard back.

Father hospitalized, mother suffered emotional breakdown

Global Affairs Canada said it was monitoring the situation in Bangladesh closely. A spokeswoman added that "there are limits'' to what any country can do for individuals who are not its citizens.

The entire situation has taken a tremendous toll on the parents, his brother said, noting that his mother has suffered an emotional breakdown and his father was hospitalized on Monday after a suspected heart attack.

"We understand that it's a national security issue, but at least if my parents could go and see him, that would be some kind of solace,'' he said. "At least communication to begin with.''